1. Field of the Invention
The present invention relates to mobile communication terminals, and more particularly an apparatus and a method for determining scanning frequency bandwidths.
2. Description of the Related Art
Generally, a mobile communication terminal communicates with a network, such as Public Land Mobile Network (hereinafter PLMN), in order to receive a service. Generally, the mobile communication terminal performs a scanning (101) operation of the entire network supporting frequency bandwidths (ranges) for a specific period of time based on a Home PLMN (hereinafter HPLMN) timer to obtain the service when power to the terminal is turned on. FIG. 1 illustrates a typical timing operation when the terminal is powered on to establish communication with the network.
The mobile communication terminal next performs a registration procedure to a highest priority network to which the terminal is connected. In the illustrated example, herein, the HPLMN is a network with the highest priority and the HPLMN is determined by IMSI information that is stored in the Subscriber Information Module (SIM) card of the mobile communication terminal.
The mobile communication terminal considers a registered PLMN as a Visited PLMN (VPLMN) when the mobile communication terminal is registered to a PLMN which is not the HPLMN and the mobile communication terminal performs scanning the frequency ranges of the network in order to find a PLMN with a higher priority than the registered PLMN.
When the mobile communication terminal is registered to a VPLMN and obtains the service, the mobile communication terminal periodically performs a scanning of the available frequency ranges (bandwidths) in order to find the PLMN with a higher priority than the registered VPLMN or the HPLMN. When the mobile communication terminal finds a PLMN with a higher priority, the mobile communication terminal performs a registration to the PLMN with the higher priority.
Typically, a scanning period is stored as an Elementary Files_Higher Priority PLMN (EF_HPPLMN) in the SIM card and the scanning period has a period from 6 minutes, as a minimum value, to 8 hours, as a maximum value.
This, when the mobile communication terminal is registered to the VPLMN, the mobile communication terminal repeatedly performs the scanning operation with a determined period until the mobile communication terminal is registered to the HPLMN.
At this time, the scanning operation is performed across the frequency bandwidths of an entire Radio Access Technology (RAT), which are supported by the mobile communication terminal, in order to find all PLMNs with higher priority than currently registered PLMN.
However, frequency bandwidths which are supported by countries are varying so that frequency bandwidths that the mobile communication terminal should support are increasing in order to provide a seamless service.
According to this, time and quantity of current, which are required for the scanning operation, are increasing due to the need for scanning broader frequency bandwidths in order to find the HPLMN associated with the mobile communication terminal.
Also, when the mobile communication terminal is located in a roaming network, a network operator prefers for the mobile communication terminal to find and be connected to a HPLMN as soon as possible due to a billing and so on. Thus, the network operator has a tendency to configure a scanning period as short as possible.
In this case, because the mobile communication terminal performs the scanning operation more frequently than a normal scanning during an identical period, a power consumption of the mobile communication terminal is increased.
That is, when the mobile communication terminal in a conventional technology obtains a service at the roaming network, a battery life of the mobile communication terminal is shortened due to a increased power consumption caused from the frequent scanning and the time required for the scanning.